Backlight voltage: 2.8~3.1V
LED lamp current: 15~20MA
LED backlight working temperature: -30~70 degrees
Dimensions and shapes: various regular shapes or special-shaped backlights can be designed according to requirements, including rectangular, hexagonal, octagonal and circular LED backlights and ultra-thin edge LED backlights.
Color: various solid colors, two-color, multi-color. Such as white, red, orange, yellow, green, blue, amber and so on.
Plate thickness: various common thicknesses, such as 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, etc.
Lighting method: plug-in lights or patch lights
Connection method: metal flexible wire, metal pin, terminal wire, FPC cable, etc.
When operating in low-light or no-light ambient conditions, an LED backlight is required to read LCD characters. The backlight can be turned "on" or "off" independently of the LCD to reduce power consumption.
LED (Light Emitting Diode) backlights are the preferred choice for segmented LCDs as they are DC (direct current) driven, do not generate EM interference and offer a long half-life.
Most designs connect the backlight to the LCD as a unit or module, but they can be manufactured and shipped separately.
LED backlights require more power than LCDs
Segment LCD displays without backlights operate as low as 2uA per square centimeter. Adding an LED backlight increases the current draw to 15mA and can go as high as 75mA or more. Therefore, most of Focus Displays' custom LCD designs incorporate transflective polarizers to make the display readable with or without an LED backlight.
LED backlight connection:
The LED backlight is DC and requires positive A (LED+) and negative K (LED-) connections independent of the LCD logic voltage. There are several ways to power the LED, three options are listed below.
LED backlight with labels:
The image below shows an LED backlight with A and K tabs that allow the backlight to be "plugged" into the customer's PCB. These tabs can then be soldered to hold the backlight in place.
LED backlight with discrete wires:
LED backlights with two discrete wires (also known as pigtails) allow customers to source backlight power from different locations. Cables can be manufactured to the desired length and contain some type of termination (connector).
LED backlight with PCB attached:
The LED backlight connected to the segment LCD can be powered through the same type of pins as the LCD. A small PCB is used to connect the LED backlight to the back of the LCD polarizer. The LCD and backlight pins can then be plugged into a single DIP socket.
In the case of limited space, or the structure does not allow the backlight to be longer than the LCD, otherwise it will not fit. When the light board is installed on the backlight, the shading area needs to be at least 4MM, but if the light is directly attached to the PCB board, the backlight hole can be left 2MM.
Another reason is that the cost is low, the lamp beads are well placed on the board, and it is much cheaper to only buy the backlight board. It saves the cost of assembling the light board to the backlight, and saves the cost of welding wires to the PCB analysis.